Vertical pillow form-fill-seal machines have been used in the past as form-fill-seal machines in which, a bag that, while being formed, is filled with package contents such as food products, and hermetically sealed to package the contents. The form-fill-seal machine shapes a packaging material that is a film of sheet form into a cylindrical shape (tube shape) using a former and a tube, and seals the overlapping vertical edges of the tube-shaped packaging material with a longitudinal sealing mechanism. Next, the form-fill-seal machine seals the bottom part of the bag using a transverse sealing mechanism, and then fills the interior of the tube-shaped packaging material with package contents. Next, the form-fill-seal machine seals the top part of the bag using a transverse sealing mechanism, and then the transverse-sealed portions are cut across the center by a cutter. The form-fill-seal machine repeatedly and continuously carries out the aforementioned actions of forming bags and filling the bags with package contents.